Real-World Gravel Aero

Gravel racing is fast and aero really matters, but it isn’t as fast as road racing so the requirements are different. The OSTRO Gravel frame is carefully optimized for the speeds at which you’ll be riding. Our team used a ‘zoned aero’ strategy which focused the front of the bike on aerodynamics because it meets clean, or freestream, air flow, and the rear of the bike on lightness, where the air flow is too chaotic and ride quality is the priority. In particular, a lot of time was spent on the head tube, where an all-new tube shape unlocked significant drag reductions by manipulating the ‘laminar separation bubble’ that occurs near the front of airfoils at lower speeds. The tech is rooted in aerospace but all you really need to know is that the OSTRO Gravel will get you to your finish line faster, and by minutes, not seconds.

45mm Tire Clearance

The OSTRO Gravel offers a generous 45mm of tire clearance in both 700c and 650b, giving you the options and possibilities to tackle the toughest routes and events. This is a real figure, with 4mm of clearance either side in accordance with ISO standards, so the OSTRO Gravel is super-capable in muddy conditions. That was proven at the queen of gravel races, the 2022 Unbound 200, where heavy rain made the course brutal and the OSTRO Gravel was ridden to a top-10 finish.

Black Inc THIRTY FOUR Carbon Gravel Wheels

The new Black Inc THIRTY FOUR wheels are - like the OSTRO Gravel itself - dedicated to speed on gravel. Their 34mm depth maximizes aero gains while keeping weight to a minimum and avoiding too tall a combined rim and tire side area, ensuring crosswind stability. They’re most aero with a 32mm tire for all-road use, yet also very effective for gravel tires up to 43mm. The internal width of 25mm allows bigger tires to take a better shape. The hookless rim is designed to make it easy to mount tubeless tires, in most cases with a regular floor pump. The rim includes a secondary shoulder which keeps the tire securely seated in the event of a rapid deflation, allowing you to come to a controlled stop. The Black Inc hubs run on CeramicSpeed bearings for ultimate efficiency.

Black Inc Integrated Aero Barstem

Aerodynamics and ergonomics - the flared Black Inc Integrated Aero Barstem takes both to new heights, because riding far and riding fast are not mutually exclusive. Its mid-depth aero profile is the outcome of tireless research and development, initially using CFD (computational fluid dynamics), then by testing prototypes in a wind tunnel. The result is that it outperforms leading brands of aero road bars and does so at an exceptionally low weight. What’s more, it’s as comfortable as it is fast, thanks to highly refined ergonomics which provide more back sweep for a natural wrist angle on the tops, more wrist clearance and hand positions thanks to the chamfered corners, a drop shape that accounts for the longer reach of the latest Shimano and SRAM shifters and a 7-degree flare that starts below the shifter mounting point. The flare adds 3cm of width in the drops, a figure carefully judged to suit all applications as the Integrated Aero Barstem is designed to pull double-duty for both the OSTRO Gravel and OSTRO VAM. For gravel, enjoy the extra control of the wider drops in descents; for road use, select your usual drop width and benefit from the much more aero position achievable on the narrower hoods. The new Integrated Aero Barstem also gains a GoPro-style computer mount, adding angle adjustment and a more supported second mount for a light or action camera.

Steering Geometry Optimized For All Tire Sizes

Many all-road and gravel bikes struggle to deliver steering that’s effective and confident both on- and off-road, typically ending up with an unsatisfying compromise of soft handling and modest tire capacity. The OSTRO Gravel breaks that mold by making the tire size an integral part of the geometry. Wider tires also have a greater outside diameter (or rolling circumference) which increases the true, or ‘resulting’ trail of a bike; narrower tires have a smaller outside diameter which reduces resulting trail. These outcomes match the handling response you want when riding those respective tires, so we designed with resulting trail as the priority. We selected a trail value on the slightly faster handling side for gravel use, given the bike’s racing focus, while prioritizing head tube angle when selecting our fork rake. This leads to a fast handling gravel bike on 43mm tires and an equally satisfying and precise all-road machine on 32s, with no low-speed wheel flop.